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VOLUME 41, № 6, 2005 (November – December )


Datsyshyn O. P. Durability and failure of solids during their cyclic contact interaction

SUMMARY. The calculational model for investigation of fracture processes and residual life estimation of solids under cyclic contact interaction has been formulated. A basis of the model are material fracture criteria during fatigue crack propagation, and also algorithms of step-by-step construction of crack propagation paths developed using a singular integral equations method of two-dimensional contact problems of the elasticity theory for bodies with curvilinear cracks. The model is realized for contact interactions of rolling and fretting fatigue. Peculiarities and causes of formation of such typical defects in rolling bodies as pitting, spalling, squat, cracking have been investigated depending on operational parameters of a rolling pair. It has been shown that both under rolling, and fretting fatigue a character of contact surface fracture and debris size are much influenced by the friction coefficient and distribution of tangential tractions between contacting bodies, cyclic crack growth resistance characteristics of material and presence of service or accidental products (water, lubricant, powdered products of fretting etc.) in the contact zone. Examples of residual durability calculation of rail steel (RSB12) and roll steels (9ХФ, GH) have been presented.

Kulchytsky-Zhyhailo R. Contact stresses in rotating bodies with account of heat production and convective heat transfer

SUMMARY. The axisymetrical contact problem of thermoelasticity for rotating bodies is considered. Heat generation in a contact zone and convective heat exchange are taken into account. The distribution of stresses is determined. The special attention is given to the maximal shear stresses and the possibility of the tension stresses existence.

Huryn S. V., Pohreliuk I. M., and Fedirko V. M. Preconditions of carboxide phase formation during titanium treatment from carbon-oxygen containing environment

SUMMARY. The thermodynamic aspects of the interaction between titanium and carbon-oxygen-containing medium has been considered. Based on the thermodynamic calculations and obtained experimental results the hypothesis of carbooxide phase formation at the titanium surface layers during thermo-diffusion saturation, which foresees the diffusion of the carbon atoms through vacancies to the metal has been proposed.

Prokopovych I. B. Constitutive equation of electric or magnetic deformation in an isotropic material

SUMMARY. For an isotropic material, the general representation and differential characteristics are constructed and investigated for the “large” free (“internal”, “inherent”) distortion depending on one scalar, e. g. thermal, and one vector, e. g. electric or magnetic, parameters of the state. In particular it is shown that the distortion is equal to deformation non-depending on the sign of vector parameter end value when the corresponding initial value is equal to zero.

Liubin O. H. Life assessment of a tribosystem “shaft-bushing”

SUMMARY. Based on solving the wear-contact problems life-times for couples nonwearing shaft–wearing bearing bush were evaluated. Results of numerical calculations of relative life-times are presented.

Bulyk I. I. and Basaraba Yu. B. Influence of hydrogen treatment on discharge properties of ZrCrNi electrodes

SUMMARY. The improvement of activation (2 charge-discharge cycles) and the increase of the discharge capacity were shown for metal-hydride electrodes on the basis of ZrCrNi alloy after homogenization of the C14 type Laves phase by partly disproportionation in hydrogen at 873 K and recombination in vacuum at 1223 K. The discharge capacity is decreased after disproportionation at 1083 K and recombination with formation of the C15 type Laves phase. Optimal milling conditions of the alloy in hydrogen by means of planetary ball mill was determined: speed of rotation – 100 rpm, milling time – 30 min.

Zavaliy I. Yu., Yurchyk M., Vovk O. M., Saldan I. V., and Kovalchuk I. V. The influence of high-energy milling on hydrogen desorption and structure of mixtures of Zr-containing materials

SUMMARY. Mass-spectrometry studies of hydrogen desorption from the mixture of powders 3ZrO0,2Hх + ZrFe2, which corresponded to the Zr4Fe2O0,6Hх overall composition and was treated by ball milling during 5 and 50 h, revealed substantial dependence of hydrogen desorption on the time of mechanical treatment. X-ray diffraction showed substantial disordering of constituent components after high-energy ball milling, The combination of mechanical treatment and hydrogen desorption from prepared mixtures did not lead to the formation of the Zr4Fe2O0,6 intermetallic suboxide as it was observed during desorption-recombination in the HDDR process.

Panasyuk V. V., Sylovaniuk V. P., and Marukha V. I. Strength of crack damaged structural elements, healed by injection methods

SUMMARY. A methodology for assessment of residual strength of cracked structural elements strengthened by injection methods has been developed. Basic parameters affecting the injection process efficiency have been established. Ways of the technology optimization are shown.

Gnyp I. P., Neprila M. V., and Voloshyn M. P. Methodical aspects of determining the electric insulation coatings elasticity

SUMMARY. Investigations of the elasticity of 12 different types of polymer protective coatings have been carried out. Under pure bending testing of rectangular plates the dielectric continuity was checked by electric spark flaw detector, constant current resistance was measured, and fracture traces appearance on the coating surface was observed by a microscope with a 30-fold magnification. It has been established that for high-elastic coatings the loss of dielectric continuity occurs under relative deformation lower by an order magnitude to compare with the cracks initiation on the surface. Using the investigation results the conclusion has been drawn that the assessment of the coating elasticity by criterion of dielectric continuity loss is the most correct and reliable approach. Attention has been paid to the methodical aspects of the mechanical testing of the specimens.

Dzioba I. R., Student O. Z., and Markov A. D. Application of SINTAP approach to evaluation of surviceability of TPP steam welded joints

SUMMARY. The serviceability of a welded joint (WJ) after ~19 104 h operation on thermal power station steam pipe-line was estimated according to the SINTAP procedure. The strength and fracture toughness parameters of the appropriate areas of WJ were used for calculation. It was assumed, that WJ was loaded by uniform tension, and in addition there were residual stresses in the WJ, and a semi-elliptical crack grows in the body metal and in the weld joint from external surface of the pipe. The critical state characteristics for the pipe element with WJ obtained using the calculation method, agree well with the expert conclusion about the reasons of steam pipe-line failure.

Sidhu S. T., Prakash S., and Agrawal R. D. Studies on the properties of high velocity oxy fuel thermal spray coatings for higher temperature applications (A review)
Shyrokov V. V., Arendar L. A., Vasyliv Kh. B., Vasyliv O. M., and Biliuk A. I. Mechanism of antifriction effect of phosphide eutectics in cast irons

SUMMARY. The microstructure and microtopography dynamics of grey cast irons and high-strength cast irons with 0.05…11 vol.% phosphide eutectic during dry and boundary (counterbody – steel 45) friction interaction have been investigated. It has been established that physico-mechanical properties of phosphorous cast irons are greatly affected by distribution and morphology of phosphide eutectics (PE). As a result PE is localized in thin (to 5 µm) subsufrace layers of metal, redistribues and its area on the surface increase by 20…30 %. The mechanism of phosphide eutectic influence on the wear-resistance of the grey and high-strength phosphorous cast irons was substantiated. Temperature flashes of phosphide eutectic inclusions cause their plastification, increase in the friction surface area and, as result, decrease in contact pressures, and also reduction in average mean integral temperature and improvement in their wear-resistance.

Krutsan H., Radkevych O. I., Melekhov R. K., and Yurkevych R. M. Assessment of resistance to stress corrosion cracking in hydrogen sulphide media of corrosion resistant steels

SUMMARY. A tendency of corrosion-resistant martensitic, martensitic-ferritic, austenitic, austenitic-martensitic and ferritic-austenitic steels to stress corrosion cracking in hydrogen sulphide containing media has been investigated. It has been established that among all tested steels austenitic chromium–nickel–molybdenum (08Х17Н15М13Т and 10Х17Н13М2Т) and ferritic-austenitic (12Х21Н5Т and 02Х22Н6АМ3) steels (see Table 1) have the highest fracture resistance: threshold stresses in NACE solution (5% NaCI + 0.5% СН3СООН, saturated with H2S, 20+2С, рН~3) are not less that 90% of the yield strength.

Balytskyi O. O. Failure of laminated gallium and indium khalcogenides
Balytskyi O. I. and Zinkovskyi A. P. A joint session of Scientific Councils on “Physicochemical mechanics of materials” and “Mechanics of deformable solids”
Luchko Yo. Yo. and Sulym H. T. The Sixth International Symposium “Mechanics and physics of fracture of building materials and structures”
Stashchuk M. H. Problems of brittle fracture mechanics
Vasyliv Kh. B. Theoretical and applied tribology
Okhota H. H. Theory of corrosion and corrosion protection
Оleh Romaniv (an obituary notice)
List of papers published in “Physicochemical Mechanics of Materials” in 2005
Authors’ index

Revised: 17.02.2006